Figure 3
Inspiratory effort during simulated unassisted spontaneous breathing (P = 0 cm H 2 O) is plotted versus the resistive loss coefficient, with compliance held constant at 0.05 L/cm H 2 O, for medical air, and two helium/oxygen mixture (78/22 or 65/35) at a) a respiratory rate (RR) of 15 breaths/min, and a tidal volume (V t ) of 500 mL, b) a respiratory rate (RR) of 20 breaths/min, and a tidal volume (V t ) of 600 mL, and c) a respiratory rate (RR) of 25 breaths/min, and a tidal volume (V t ) of 700 mL. For medical air, data is also shown for positive pressure support of 10 or 15 cm H2O, supplied with a positive end-expiratory pressure of 5 cm H2O. Error bars represent standard deviations around mean values.